Short answer: the KZ Libra. It ranks #901 of 1369 in-ear headphones by sound quality, rated 3.4/5, at $2; the Harmonic Empire Cai Wenji ranks #956, rated 3.3/5, at $1.99. The price gap is small enough that the sound-quality ranking should decide it.
The case for the KZ Libra: A broadly balanced tuning with a preference score of 66 against the Harman target. The catch: An uneven response, 2.3 dB standard deviation from target.
The case for the Harmonic Empire Cai Wenji: A published AutoEQ preset corrects its response toward the Harman target, so a few minutes of EQ setup closes most of the gap. The catch: Treble about 5 dB below target from 3 to 10 kHz, which can sound dull or veiled next to brighter headphones.
Buy the KZ Libra. It is rated higher for sound quality, and the $0.01 you would save on the Harmonic Empire Cai Wenji does not close the gap.
Still deciding? The full Headphones rankings cover every ranked option.
A broadly balanced tuning with a preference score of 66 against the Harman target.
KZ Audio eBay
A published AutoEQ preset corrects its response toward the Harman target, so a few minutes of EQ setup closes most of the gap.
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Specifications Side By Side
| KZ Libra | Harmonic Empire Cai Wenji | |
|---|---|---|
| Price | 2.00 | 1.99 |
| Ranked | #901 of 1369 in In-Ear Headphones | #956 of 1369 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 66 (median of 4 squig.link measurements, calibrated to AutoEQ) | 65 (median of 7 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 2.28 dB standard deviation | 2.58 dB standard deviation |
| Tonal Tilt | -0.86 (negative is warmer, positive brighter) | -0.81 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+1.9 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-0.9 dB at 30 Hz) |
| Driver Type | Dynamic | Dynamic |
| Drivers | 1 x 10mm ultra-wideband dynamic driver | 1 x 10mm PEEK+PU dynamic driver |
| Impedance | 25 ohms | 16 ohms |
| Sensitivity | 108 dB | 114 dB |
| Frequency Response | 20Hz - 40kHz | 20Hz - 20kHz |
| Connection | Wired | Wired |
| Weight | - | 0 lbs (3.9 g) |
Frequency Response Compared
Both headphones’ measurements overlaid on the Harman target. Above the target sounds louder in that range, below it quieter. Each curve is the median of several independent measurements, shifted so its 500 Hz to 2 kHz average sits at 0 dB, so only the tuning is compared.
Measurement data: the KZ Libra from boizoff, eplv, obodio, soundcheck39, theaudiostore and treblewellxtended; the Harmonic Empire Cai Wenji from aftersound, bassaudio, csi-zone, dvewlsh, fernandagunsan, hbb and soundignity, all via squig.link.
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